The present invention relates to the field of reclosable packages and an apparatus used to apply closure elements to a packaging film and form such packages. More particularly, the invention relates to a method and apparatus for applying reclosable profile elements and a tear strip element to a packaging film in a form, fill and seal packaging operation.
One method of forming packages is known as the form, fill and seal method, wherein a continuous length of film is fed forwardly and downwardly over a forming tube, with the marginal edges of the sheet of film being sealed to each other. The thus formed tube of film is cross-sealed, and contents are dropped into the package through the tubular mandrel over which the packaging film is formed. An additional cross seal above the contents completes the package, which is then severed from the tubular film.
Reclosable packages having male and female cooperating reclosable elements along an opening or seam of the package have been known for some time. Similarly, the use of a tear strip element along an opening or seam of a package has been known for some time.
There are several advantages to forming product-containing packages with such reclosable fasteners. As such, several methods have been developed to produce packages with reclosable fasteners on form, fill and seal equipment.
Many of these methods utilize packaging film which already includes the reclosable profile element affixed to the packaging film, or uses packaging film wherein the reclosable element is formed integral with the film web. By way of example, the following U.S. Patents disclose various methods of utilizing such packaging film in forming reclosable packages:
U.S. Pat. No. 4,840,012 discloses a method and apparatus for improving the advancement of packaging film, in a form, fill and seal apparatus.
U.S. Pat. No. 4,698,954 discloses a guide mechanism disposed within the packaging film to align the feeding of the film into the filling portion of the form, fill and seal apparatus.
U.S. Pat. No. 4,727,709 discloses a steering, joining and guiding mechanism for joining together opposing rib and groove fastener elements present along the longitudinal border on a traveling continuous packaging film as the film is formed into a package.
U.S. Pat. No. 4,745,731 discloses a method and apparatus for forming reclosable storage containers wherein interconnecting members of a profile element, present along the outer border of the film, must be aligned after the film is wrapped about a forming shoulder of a form, fill and seal apparatus.
U.S. Pat. No. 4,625,496 discloses a method of moving a sheet of packaging film having a profile element integral therewith over a forming shoulder of a form, fill and seal apparatus.
U.S. Pat. No. 4,617,683 discloses reclosable bags and a method of making the same. The bags are formed from material having an extruded reclosable plastic fastener extending across the longitudinal formation axis of the packaging material prior to formation of the bags.
U.S. Pat. No. 4,790,126 discloses a fill and seal machine for reclosable bags wherein the bags are made from packaging material having zipper profiles attached equidistant from the film edges prior to feeding the material into the form, fill and seal apparatus. The open zipper profile must then be closed during an indexing cycle on the form, fill and seal apparatus.
One problem with methods and apparatus which use packaging film with reclosable profiles already attached to the packaging film is that the desired combined packaging film and reclosable profile shape must be obtained for all desired combinations of packaging film, film widths, profile shape and profile locations. Another problem is that it is more bulky to store the combined profile and film than to store the elements separately. Similar problems arise with methods and apparatus which use packaging film with a tear strip element already attached to the packaging film.
Several methods have been developed wherein profiles are attached to a packaging film just prior to the introduction of the packaging film into the form fill and seal apparatus. For example, see U.S. Pat. No. 4,355,494, which discloses an apparatus for making reclosable packages wherein the reclosable packages are formed by applying the profile element to the longitudinal edges of a traveling web of packaging material. The profile elements are then joined together by multiple roller pairs which guide the profiles into engagement between a pair of press rolls.
While these methods overcome the above noted problems, they require additional equipment to compensate for the difference in the intermittent operation of the form, fill and seal equipment and the preferred continuous adhering of the reclosable profile strips to the packaging film.
Another prior art method applies the profile strips intermittently. U.S. Pat. No. 4,709,533 and 4,894,975 disclose a method and apparatus for forming a reclosable package wherein a reclosable profile is adhered to the outer edges of the packaging film as the edges are brought together and a fin seal is formed on a form, fill and seal machine.
One disadvantage with this disclosed method of the '533 patent of applying the profile strips while the packages are being formed is that the resulting packages have the reclosable element between the fin seal and the package contents. It would be preferable to be able to place the reclosable profile at other places on the package structure, such as at a package side opposite the fin seal on a three-sided seal package, or on one of the side edges of a pillow package. It is also preferable to affix a tear strip element to the package in relatively close proximity to the reclosable profile elements on the package structure.